/*
 * jdinput.c
 *
 * Copyright (C) 1991-1995, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains input control logic for the JPEG decompressor.
 * These routines are concerned with controlling the decompressor's input
 * processing (marker reading and coefficient decoding).  The actual input
 * reading is done in jdmarker.c, jdhuff.c, and jdphuff.c.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/* Private state */

typedef struct
{
	struct jpeg_input_controller pub;	/* public fields */

	boolean         inheaders;	/* TRUE until first SOS is reached */
} my_input_controller;

typedef my_input_controller *my_inputctl_ptr;


/* Forward declarations */
METHODDEF int consume_markers JPP((j_decompress_ptr cinfo));


/*
 * Routines to calculate various quantities related to the size of the image.
 */

LOCAL void initial_setup(j_decompress_ptr cinfo)
/* Called once, when first SOS marker is reached */
{
	int             ci;
	jpeg_component_info *compptr;

	/* Make sure image isn't bigger than I can handle */
	if((long)cinfo->image_height > (long)JPEG_MAX_DIMENSION || (long)cinfo->image_width > (long)JPEG_MAX_DIMENSION)
		ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int)JPEG_MAX_DIMENSION);

	/* For now, precision must match compiled-in value... */
	if(cinfo->data_precision != BITS_IN_JSAMPLE)
		ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);

	/* Check that number of components won't exceed internal array sizes */
	if(cinfo->num_components > MAX_COMPONENTS)
		ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components, MAX_COMPONENTS);

	/* Compute maximum sampling factors; check factor validity */
	cinfo->max_h_samp_factor = 1;
	cinfo->max_v_samp_factor = 1;
	for(ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++)
	{
		if(compptr->h_samp_factor <= 0 || compptr->h_samp_factor > MAX_SAMP_FACTOR ||
		   compptr->v_samp_factor <= 0 || compptr->v_samp_factor > MAX_SAMP_FACTOR)
			ERREXIT(cinfo, JERR_BAD_SAMPLING);
		cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor, compptr->h_samp_factor);
		cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor, compptr->v_samp_factor);
	}

	/* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
	 * In the full decompressor, this will be overridden by jdmaster.c;
	 * but in the transcoder, jdmaster.c is not used, so we must do it here.
	 */
	cinfo->min_DCT_scaled_size = DCTSIZE;

	/* Compute dimensions of components */
	for(ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++)
	{
		compptr->DCT_scaled_size = DCTSIZE;
		/* Size in DCT blocks */
		compptr->width_in_blocks = (JDIMENSION)
			jdiv_round_up((long)cinfo->image_width * (long)compptr->h_samp_factor, (long)(cinfo->max_h_samp_factor * DCTSIZE));
		compptr->height_in_blocks = (JDIMENSION)
			jdiv_round_up((long)cinfo->image_height * (long)compptr->v_samp_factor, (long)(cinfo->max_v_samp_factor * DCTSIZE));
		/* downsampled_width and downsampled_height will also be overridden by
		 * jdmaster.c if we are doing full decompression.  The transcoder library
		 * doesn't use these values, but the calling application might.
		 */
		/* Size in samples */
		compptr->downsampled_width = (JDIMENSION)
			jdiv_round_up((long)cinfo->image_width * (long)compptr->h_samp_factor, (long)cinfo->max_h_samp_factor);
		compptr->downsampled_height = (JDIMENSION)
			jdiv_round_up((long)cinfo->image_height * (long)compptr->v_samp_factor, (long)cinfo->max_v_samp_factor);
		/* Mark component needed, until color conversion says otherwise */
		compptr->component_needed = TRUE;
		/* Mark no quantization table yet saved for component */
		compptr->quant_table = NULL;
	}

	/* Compute number of fully interleaved MCU rows. */
	cinfo->total_iMCU_rows = (JDIMENSION) jdiv_round_up((long)cinfo->image_height, (long)(cinfo->max_v_samp_factor * DCTSIZE));

	/* Decide whether file contains multiple scans */
	if(cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode)
		cinfo->inputctl->has_multiple_scans = TRUE;
	else
		cinfo->inputctl->has_multiple_scans = FALSE;
}


LOCAL void per_scan_setup(j_decompress_ptr cinfo)
/* Do computations that are needed before processing a JPEG scan */
/* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
{
	int             ci, mcublks, tmp;
	jpeg_component_info *compptr;

	if(cinfo->comps_in_scan == 1)
	{

		/* Noninterleaved (single-component) scan */
		compptr = cinfo->cur_comp_info[0];

		/* Overall image size in MCUs */
		cinfo->MCUs_per_row = compptr->width_in_blocks;
		cinfo->MCU_rows_in_scan = compptr->height_in_blocks;

		/* For noninterleaved scan, always one block per MCU */
		compptr->MCU_width = 1;
		compptr->MCU_height = 1;
		compptr->MCU_blocks = 1;
		compptr->MCU_sample_width = compptr->DCT_scaled_size;
		compptr->last_col_width = 1;
		/* For noninterleaved scans, it is convenient to define last_row_height
		 * as the number of block rows present in the last iMCU row.
		 */
		tmp = (int)(compptr->height_in_blocks % compptr->v_samp_factor);
		if(tmp == 0)
			tmp = compptr->v_samp_factor;
		compptr->last_row_height = tmp;

		/* Prepare array describing MCU composition */
		cinfo->blocks_in_MCU = 1;
		cinfo->MCU_membership[0] = 0;

	}
	else
	{

		/* Interleaved (multi-component) scan */
		if(cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
			ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan, MAX_COMPS_IN_SCAN);

		/* Overall image size in MCUs */
		cinfo->MCUs_per_row = (JDIMENSION) jdiv_round_up((long)cinfo->image_width, (long)(cinfo->max_h_samp_factor * DCTSIZE));
		cinfo->MCU_rows_in_scan = (JDIMENSION)
			jdiv_round_up((long)cinfo->image_height, (long)(cinfo->max_v_samp_factor * DCTSIZE));

		cinfo->blocks_in_MCU = 0;

		for(ci = 0; ci < cinfo->comps_in_scan; ci++)
		{
			compptr = cinfo->cur_comp_info[ci];
			/* Sampling factors give # of blocks of component in each MCU */
			compptr->MCU_width = compptr->h_samp_factor;
			compptr->MCU_height = compptr->v_samp_factor;
			compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
			compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_scaled_size;
			/* Figure number of non-dummy blocks in last MCU column & row */
			tmp = (int)(compptr->width_in_blocks % compptr->MCU_width);
			if(tmp == 0)
				tmp = compptr->MCU_width;
			compptr->last_col_width = tmp;
			tmp = (int)(compptr->height_in_blocks % compptr->MCU_height);
			if(tmp == 0)
				tmp = compptr->MCU_height;
			compptr->last_row_height = tmp;
			/* Prepare array describing MCU composition */
			mcublks = compptr->MCU_blocks;
			if(cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU)
				ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
			while(mcublks-- > 0)
			{
				cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
			}
		}

	}
}


/*
 * Save away a copy of the Q-table referenced by each component present
 * in the current scan, unless already saved during a prior scan.
 *
 * In a multiple-scan JPEG file, the encoder could assign different components
 * the same Q-table slot number, but change table definitions between scans
 * so that each component uses a different Q-table.  (The IJG encoder is not
 * currently capable of doing this, but other encoders might.)  Since we want
 * to be able to dequantize all the components at the end of the file, this
 * means that we have to save away the table actually used for each component.
 * We do this by copying the table at the start of the first scan containing
 * the component.
 * The JPEG spec prohibits the encoder from changing the contents of a Q-table
 * slot between scans of a component using that slot.  If the encoder does so
 * anyway, this decoder will simply use the Q-table values that were current
 * at the start of the first scan for the component.
 *
 * The decompressor output side looks only at the saved quant tables,
 * not at the current Q-table slots.
 */

LOCAL void latch_quant_tables(j_decompress_ptr cinfo)
{
	int             ci, qtblno;
	jpeg_component_info *compptr;
	JQUANT_TBL     *qtbl;

	for(ci = 0; ci < cinfo->comps_in_scan; ci++)
	{
		compptr = cinfo->cur_comp_info[ci];
		/* No work if we already saved Q-table for this component */
		if(compptr->quant_table != NULL)
			continue;
		/* Make sure specified quantization table is present */
		qtblno = compptr->quant_tbl_no;
		if(qtblno < 0 || qtblno >= NUM_QUANT_TBLS || cinfo->quant_tbl_ptrs[qtblno] == NULL)
			ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
		/* OK, save away the quantization table */
		qtbl = (JQUANT_TBL *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(JQUANT_TBL));
		MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL));
		compptr->quant_table = qtbl;
	}
}


/*
 * Initialize the input modules to read a scan of compressed data.
 * The first call to this is done by jdmaster.c after initializing
 * the entire decompressor (during jpeg_start_decompress).
 * Subsequent calls come from consume_markers, below.
 */

METHODDEF void start_input_pass(j_decompress_ptr cinfo)
{
	per_scan_setup(cinfo);
	latch_quant_tables(cinfo);
	(*cinfo->entropy->start_pass) (cinfo);
	(*cinfo->coef->start_input_pass) (cinfo);
	cinfo->inputctl->consume_input = cinfo->coef->consume_data;
}


/*
 * Finish up after inputting a compressed-data scan.
 * This is called by the coefficient controller after it's read all
 * the expected data of the scan.
 */

METHODDEF void finish_input_pass(j_decompress_ptr cinfo)
{
	cinfo->inputctl->consume_input = consume_markers;
}


/*
 * Read JPEG markers before, between, or after compressed-data scans.
 * Change state as necessary when a new scan is reached.
 * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
 *
 * The consume_input method pointer points either here or to the
 * coefficient controller's consume_data routine, depending on whether
 * we are reading a compressed data segment or inter-segment markers.
 */

METHODDEF int consume_markers(j_decompress_ptr cinfo)
{
	my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
	int             val;

	if(inputctl->pub.eoi_reached)	/* After hitting EOI, read no further */
		return JPEG_REACHED_EOI;

	val = (*cinfo->marker->read_markers) (cinfo);

	switch (val)
	{
		case JPEG_REACHED_SOS:	/* Found SOS */
			if(inputctl->inheaders)
			{					/* 1st SOS */
				initial_setup(cinfo);
				inputctl->inheaders = FALSE;
				/* Note: start_input_pass must be called by jdmaster.c
				 * before any more input can be consumed.  jdapi.c is
				 * responsible for enforcing this sequencing.
				 */
			}
			else
			{					/* 2nd or later SOS marker */
				if(!inputctl->pub.has_multiple_scans)
					ERREXIT(cinfo, JERR_EOI_EXPECTED);	/* Oops, I wasn't expecting this! */
				start_input_pass(cinfo);
			}
			break;
		case JPEG_REACHED_EOI:	/* Found EOI */
			inputctl->pub.eoi_reached = TRUE;
			if(inputctl->inheaders)
			{					/* Tables-only datastream, apparently */
				if(cinfo->marker->saw_SOF)
					ERREXIT(cinfo, JERR_SOF_NO_SOS);
			}
			else
			{
				/* Prevent infinite loop in coef ctlr's decompress_data routine
				 * if user set output_scan_number larger than number of scans.
				 */
				if(cinfo->output_scan_number > cinfo->input_scan_number)
					cinfo->output_scan_number = cinfo->input_scan_number;
			}
			break;
		case JPEG_SUSPENDED:
			break;
	}

	return val;
}


/*
 * Reset state to begin a fresh datastream.
 */

METHODDEF void reset_input_controller(j_decompress_ptr cinfo)
{
	my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;

	inputctl->pub.consume_input = consume_markers;
	inputctl->pub.has_multiple_scans = FALSE;	/* "unknown" would be better */
	inputctl->pub.eoi_reached = FALSE;
	inputctl->inheaders = TRUE;
	/* Reset other modules */
	(*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
	(*cinfo->marker->reset_marker_reader) (cinfo);
	/* Reset progression state -- would be cleaner if entropy decoder did this */
	cinfo->coef_bits = NULL;
}


/*
 * Initialize the input controller module.
 * This is called only once, when the decompression object is created.
 */

GLOBAL void jinit_input_controller(j_decompress_ptr cinfo)
{
	my_inputctl_ptr inputctl;

	/* Create subobject in permanent pool */
	inputctl = (my_inputctl_ptr) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, SIZEOF(my_input_controller));
	cinfo->inputctl = (struct jpeg_input_controller *)inputctl;
	/* Initialize method pointers */
	inputctl->pub.consume_input = consume_markers;
	inputctl->pub.reset_input_controller = reset_input_controller;
	inputctl->pub.start_input_pass = start_input_pass;
	inputctl->pub.finish_input_pass = finish_input_pass;
	/* Initialize state: can't use reset_input_controller since we don't
	 * want to try to reset other modules yet.
	 */
	inputctl->pub.has_multiple_scans = FALSE;	/* "unknown" would be better */
	inputctl->pub.eoi_reached = FALSE;
	inputctl->inheaders = TRUE;
}
